1. Field of the Invention
This invention relates to generating a ratio clock signal using a global clock signal. More particularly, this invention relates to generating a ratio clock signal at any integer divided by two of a global clock signal.
2. Description of Background
It is common for an integrated circuit chip (chip) to operate with multiple different clock speeds. Often, chip architecture allows different regions of the chip to have different clock speeds. To achieve multiple different clock speeds, a chip may employ multiple clock grids throughout the entire chip with each clock grid producing a distinct clock speed. However, employing multiple clock grids creates additional expense for chip production. Thus, to keep costs down, it has been common practice to use a single clock grid to generate a global clock and obtain different clock speeds by developing ratio clock speeds at a specific ratio to the global clock.
It is common to use external control signals to develop derivative clock speeds at a ratio to the global clock. Additionally, absent external control signals, derivative clock speeds are generally limited to having whole number ratios to the global clock of, for example, 2-to-1, 4-to-1, etc. Additionally, complex circuits used to generate derivative clock speeds may create a time delay between the global clock and the derivative clock.
Thus, to overcome the above mentioned problems, it is desirable to develop a system and method for local generation of a derivative clock speed having other than a whole number ratio to the global clock.